[GitHub] [hbase] Apache9 commented on a change in pull request #3803: HBASE-26304: Reflect out of band locality improvements in metrics and balancer

[GitBox <gi...@apache.org>]

Apache9 commented on a change in pull request #3803:
URL: https://github.com/apache/hbase/pull/3803#discussion_r752329695



##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/InputStreamBlockDistribution.java
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@@ -0,0 +1,143 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.regionserver;
+
+import com.google.errorprone.annotations.RestrictedApi;
+import java.io.IOException;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.hbase.HDFSBlocksDistribution;
+import org.apache.hadoop.hbase.io.FileLink;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.apache.hadoop.hbase.util.FSUtils;
+import org.apache.hadoop.hdfs.client.HdfsDataInputStream;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Computes the HDFSBlockDistribution for a file based on the underlying located blocks
+ * for an HdfsDataInputStream reading that file. This computation may involve a call to
+ * the namenode, so the value is cached based on
+ * {@link #HBASE_LOCALITY_INPUTSTREAM_DERIVE_CACHE_PERIOD}.
+ */
+@InterfaceAudience.Private
+public class InputStreamBlockDistribution {
+  private static final Logger LOG = LoggerFactory.getLogger(InputStreamBlockDistribution.class);
+
+  private static final String HBASE_LOCALITY_INPUTSTREAM_DERIVE_ENABLED =
+    "hbase.locality.inputstream.derive.enabled";
+  private static final boolean DEFAULT_HBASE_LOCALITY_INPUTSTREAM_DERIVE_ENABLED = false;
+
+  private static final String HBASE_LOCALITY_INPUTSTREAM_DERIVE_CACHE_PERIOD =
+    "hbase.locality.inputstream.derive.cache.period";
+  private static final int DEFAULT_HBASE_LOCALITY_INPUTSTREAM_DERIVE_CACHE_PERIOD = 60_000;
+
+  private final FSDataInputStream stream;
+  private final StoreFileInfo fileInfo;
+  private final int cachePeriodMs;
+
+  private HDFSBlocksDistribution hdfsBlocksDistribution;
+  private long lastCachedAt;
+  private boolean streamUnsupported;
+
+  public InputStreamBlockDistribution(FSDataInputStream stream, StoreFileInfo fileInfo) {
+    this.stream = stream;

Review comment:
       So where is the stream constructed? What if it is closed but we still want to compute locality? Is this possible?




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